by: wael fareed-batch 5 - uni-kassel.de · wael fareed-batch 5 supervisors: prof. dr. dirk dahlhaus...

Voltage and Time Dependence of The Potential Induced Degradation

Effect For Different Types of Solar Modules

REMENA Master Thesis

By:

Wael Fareed-Batch 5Supervisors:

Prof. Dr. Dirk Dahlhaus Prof. Dr. Iman El Mahallawi Prof. Dr. Adel Khalil

Prof. Dr. Hans J. Möller

Examiners Committee:

09/12/2014

Prof. Dr. Iman El Mahallawi

Prof. Dr. Sayed Kaseb

Dr. Hani Elnokraschy

Wael Fareed REMENA batch#5

Raykov, Detection of PID, Intersolar 2014

Outline

Goal and objective of the research project

Literature review

Methodology

Finding and results

Conclusion and recommendations

Wael Fareed REMENA batch#5 109/12/2014

Goal and objective of the research

The objective of the study is to investigate the potential induced degradation

problem on different types of solar modules under dependency of varying

time and voltage.

Study Scope

Conducting the performance measurements on different kinds of solar modules (mini silicon

module , CdTe modules and 60 cells silicon modules).

• Leakage current measurements for different module types.

• Characterization of the tested different module types.

• Taking a closer look at the PID effect by using electroluminescence image.

• Analyses of the experimental data to obtain the PID effect on the different module

types.Wael Fareed REMENA batch#5 209/12/2014

Outline


Literature review

Methodology

Finding and results



What is the PID?

Potential Induced Degradation (PID) is an undesirable property of some solar

Modules which the modules can lose more than 40%.


Influencing system level Influencing on module level Influencing on cell level

Voltage EVA encapsulation AR-Coating

Temperature Front glass sheet Emitter depth

Humidity Back sheet Type of base doping

Grounding. Module design

Classification of the affected parameters on PID effect:

Table : classification of the affected parameters on PID effect[1]

[1]Schüetze, et al, Laboratory Study of Potential Induced

Degradation of SiliconPhotovoltaic Modules, Q-Cells

1-System level

[IEEE PID Paper 2010 Pingel Solon]

EL image of a panel positions with negative and positive grounding


2-Panel level

[IEEE PID Paper 2010 Pingel Solon]

Panel test setup for PID Leakage current paths

PID cause levels


J.A. del Cueto et al’’Degradation of Photovoltaic Modules Under High

Voltage Stress in the Field’’Calfornia August 1-5, 2010

Leakage currents at different polarities (+) , (-) 600VDC for c-Si modules against inverse absolute

module temperature , in three bands of relative humidity values , 10%, 50% , and 95%

Outline


Literature review

Methodology

Finding and results



Tested modules types

1-Mini modules (1 cell)

• 2 modules-refrence glass/back sheet (M1,M2)

• 1 module-reference glass/reference glass (M3)

• 1 module-special glass/back sheet (M4)

2-standard silicon modules (60 cells)

• 1 new mono-crystalline module (a)

• 1new poly-crystalline module (b)

• 2 stressed (poly-crystalline) modules(DHT,TCT) (c,d)

3-Cadmium telluride (CdTe)

• 2 tested outdoors CdTe modules


09/12/2014 Wael Fareed REMENA batch#5 9

The work test sequence

Outline


Literature review

Methodology

Finding and results



0

1

2

3

4

5

6

7

8

9

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Cu

rren

t (A

)

Voltage(V)

100w/m2

200w/m2

500w/m2

1000w/m2

100w/m2

200w/m2

500w/m2

1000w/m2

Inverse of the slope

gives Rs

Inverse of the

slope gives Rsh

First mini module I-V curve

0

5

10

15

20

25

30

35

40

45

50

0 40 80 120 160

∆P

(%

)

Time (h)

100I-∆p(t)

200I-∆p(t)

500I-∆p(t)

1000I-∆p(t)

4.31%

9.72%

20.96%

45.45%

First mini module IV curves comparison in different

intensities flash measurement between before PID with

solid lines and after (-2kv- 139hour) PID test with dotted

lines test

First mini module PID power

losses progress percentage at

different flash test


All mini modules power loss and

leakage current

Module Type

∆P at

Different I

M1(Reference

glass/back sheet)

139hr

M2(Reference

glass/back sheet)

67hr

M3(Glass/Glass)

140hr

M4(Special glass/back sheet)

115hr

∆P(%) at 100W/m2 45.45 9.97 48.33 43.01

∆P(%) at 200W/m2 20.96 4.63 22.52 21.70

∆P(%) at 500W/m2 9.72 2.03 10.12 10.81

∆P(%) at 1000W/m2 4.39 0.41 4.04 5.52

Table: Comparison between the tested mini modules in power losses by using different

flash tests

All investigated mini modules leakage

current over time of experiments with the

same conditions


0

0.02

0.04

0.06

0.08

0.1

0.12

0 50 100 150

I (µ

A)

Time (h)

M1

M2

M3

M4

4%

0,4%

5,5%

4,4%

Standard silicon modules

results

The characterizations data for the first standard module (new mono-crystalline) pre and post the

high voltage test was recorded as shown in table.

Voc(V) Isc(A) Vm(V) FF(%) Eff. (%) Pm(W) Rsh() Rs() Plosses (%)

Before PID 37.75 8.67 29.99 74.32 16.66 243.32 625 0.54

After-1kv ,203 h 32.54 8.33 21.23 39.08 7.26 105.79 7.60 1.30 56.52

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25 30 35 40

Cu

rren

t (A

)

Voltage (V)

IV curve for fresh mono

before

After-1kv,44hr

After-1kv,66hr

After-1kv,88hr

After-1kv,158hr

After-1kv,203hr

Rsh=inverse the slope

Rs=inverse the slope

ISC

VOC

Im,Vm

IV characterization curve

for the fresh mono

crystalline before and

after the PID test

Mono-crystalline module


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)

Electroluminescence

High Current Pass

Power loss

∆P=0%

Mono-Crystalline Power Loss


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)

Electroluminescence Power loss

∆P=2%

High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)


∆P=11%

High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)


∆P=14%

High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)


∆P=23%

High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)

∆P=26%


High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)

∆P=34%


High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)


∆P=35%

High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)


∆P=51,5%

High Current Pass



High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)

∆P=52%

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)


∆P=54,9%

High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)

∆P=55,2%


High Current Pass


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

po

wer

lo

ss (

%)

Time (h)

∆P=57%


High Current Pass


The characterizations data for the second standard module (new Poly-crystalline) pre

and post the high voltage test was recorded as shown in table.

Poly-crystalline module

Voc(V) Isc(A) Vm(V) FF(%) Eff.(%) Pm(W) Rsh() Rs() Plosses(%)

Before PID 37.21 8.81 29.447 72.95 16.37 239.14 125 0.53

After-1kv ,186 h 37.07 8.81 28.84 67.30 15.05 219.78 83 0.58 8

0

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40

Cu

rren

t (A

)

Voltage (V)

Poly IV PID Curve

Before PID

After-1kv,5hr

After-1kv,22hr

After-1kv,45hr

After-1kv,115hr

After-1kv,138hr

After-1kv,161hr

After-1kv,186hr

Rs=inverse slope

Rsh=inverse slope

IV characterization curve for

the fresh poly crystalline

module before and after the

PID test


00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)

∆P=0%


High Current Pass

Poly-Crystalline Power Loss


00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)

∆P=0%


High Current Pass


00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)


∆P=4.1%

High Current Pass


00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)


∆P=5%

High Current Pass



∆P=5.2%

00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)

High Current Pass


00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)


∆P=6.3%

High Current Pass


00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)

∆P=6.5%


High Current Pass


00

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)

∆P=8%


High Current Pass


Electroluminescence

Mono High

Current Pass

Poly High

Current Pass

Mono and Poly power loss comparison


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Po

wer

lo

ss (

%)

Time (h)

Power Loss Comparison

Mono power loss

Poly power loss55%

8%

ARC observation

Comparison between the highly degrade new mono-crystalline module

(right) and the lower degrade new poly-crystalline module (left)


TCT stressed module with its photography view (Right) and its EL image after (External Voltage= -

1000V, T=25ºC±5, RH=45%±5 and t=89 hours) PID test


1-Time dependence test comparison

All standard silicon modules comparison

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200 220

Pow

er loss

(%

)

Time (h)

Poly power losses

Mono power losses

TCT power losses

DHT power losses

8%

57%

80%89%

39%

4%

0

1

2

3

4

5

6

7

8

9

10

0 20 40 60 80 100 120 140 160 180 200 220

I (µ

A)

Time (h)

DHT leakage current

Poly leakage current

Mono leakage current

TCT leakage current

All the standards

modules under Time

dependence PID test

comparison for

voltage losses (top)

and leakage current

(bottom)


2-Voltage dependence test comparison

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

Pow

er loss

(%

)

External Voltage (kV)

Poly voltage dep. losses

Mono voltage dep. losses

TCT voltage dep. losses

DHT voltage dep. losses

All the standards

modules under

Voltage dependence

PID test comparison

for power losses

y = 10.233x - 3.3699

R² = 0.9973

y = 0.1234x2 + 14.476x - 8.919

R² = 0.9911

y = 0.7465x2 - 3.7596x + 13.532

R² = 0.993

y = 10.626x - 14.111

R² = 0.9904

0

20

40

60

80

100

120

140

160

0 2 4 6 8 10 12

I (µ

A)

External Voltage (kV)

DHT Voltage dep. leakage

TCT Voltage dep. leakage

Poly Voltage dep. leakage

Mono Voltage dep. leakage

All the standards

modules under Voltage

dependence PID test

comparison for and

leakage current



IV Curves for the first CdTe

module

Figure: I-V curve for M9 module before and after PID test with different external voltages

(a) 100W/m2 measure (b) 1000W/m2.

Protect the front glass with sprayer to prevent:

• Dust accumulations

• Water adsorption

CdTe sprayed module at

45º tilt angle

CdTe non sprayed

module at 45º tilt angle


Outdoor test

Outline


Literature review

Methodology

Finding and results




Conclusions

ARC is another factor beside the leakage current which both affect on PID.

The leakage current for all modules was increasing during the time dependent PID test.

The pre-stressed modules showed a higher degradation during the time dependence test

than the new modules.

Leakage currents were observed to be constant after beginning the PID test for the

accelerated situation, while in new modules it was slightly decreasing over time.

No additional destruction was observed at the higher stressed voltages(2-10kV).

Recommendations for future work

Investigate the PID on cells with the same aspects (same manufacturing

process) but different AR coating thickness.

Investigate any kind of materials to be sprayed on the module front glass

surface which can be able to protect from PID due to increased glass

conductivity by humidity.

Further investigations on CdTe modules, since it completely resists the PID

phenomenon during my investigations.

Avoid applying bias voltage to the PV module by grounding the negative pole

of the PV string array and using a transformer inverter [2](expensive solution).

[2] Ivo Kastle, “Dealing with high voltage

stress”, PV Magazin , 2011


by: wael fareed-batch 5 - uni-kassel.de · wael fareed-batch 5 supervisors: prof. dr. dirk dahlhaus...

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